Aqueous inks have been used in the printing industry for limited commercial print applications. An increase in the use of aqueous inks is due in part to environmental concerns about volatile organic compounds (VOC's) that solvent based inks emit when dried. For print application on paper and other absorbent surfaces, the water is partially absorbed by the surface and this makes drying the ink after printing quicker. For non-absorbent surfaces, the use of aqueous based inks sometimes can create performance issues and also, it is more difficult to quickly dry these inks when the ink sits on top of the surface.
For printing processes that use aqueous inks, often the paper is coated to prevent the paper from deforming in the presence of the water. These coated papers still are somewhat absorbent and allow the aqueous vehicle to partially penetrate the surface. Non-absorbent surfaces that keep the water based vehicle on the surface include plastic films, metal films, and similar surfaces. In these surfaces, the printed material is heat treated to remove the vehicle or exposed to ultraviolet light after printing, but if the physical properties of the ink composition do not assist in the adherence of the ink to the surface, there will be poor performance of the ink during and after printing. Under such circumstances, it is desirable for the images on the non-absorbent surface to have long term durability. Long term durability refers to the ability of the ink to remain on the final product and resist water exposure, highlighting, rubbing, scratching, and other abrasions. During printing, there is a tendency for the ink to be disturbed by shear stresses as the printed product moves through subsequent cylinders and/or other elements of the high speed printing press.